BIRDS. 73 



vegetable growth, owing to the very caustic nature of 

 their dung, which is often deposited in large quantities 

 in one place. In regions where they breed they also 

 devour both ripe and unripe grain. Where they only 

 occur in autumn, they scrape potatoes, turnips, and 

 carrots out of the ground in order to eat them. Flocks 

 of geese fly in a slanting line or in the form of a 

 ploughshare. 



Among Swimming Bucks damage is only done by 

 the Wild Duck {Anas boschas). It breeds wherever 

 there are fresh waters. Nests amongst grasses or 

 swamp-plants, or in a tree. The wild ducks remain 

 the whole winter as long as the waters are not frozen, 

 otherwise they go off for a short time to the south. 

 Food : the tops of stems, buds, leaves of various water- 

 plants, also barley, oats, and other grain; water- 

 insects, fish, and fish-spawn. These ducks also do 

 damage in cornfields by treading down and cracking 

 the plants. 



Family : Longipennes (Gulls). 



Usually swimming feet. Legs tolerably long, adapted 

 for wading (Fig. 45). Wings long, pointed. Beak 

 laterally compressed. Young nestlings (p. 51). Breed 

 in larger or smaller flocks, usually on the coast, occa- 

 sionally on the margin of fresh waters. They chiefly 

 feed on fish, worms, molluscs, and Crustacea; some- 

 times, in the case of a few species, on young birds and 

 eggs, as well as mice and other small mammals. Gulls 

 are usually of no importance in agriculture ; but the 

 Black-headed Gull (Larus ridibundus), which breeds 

 on the banks of lakes and rivers, devours many cock- 

 chafers and other noxious insects. The Herring Gull 

 (Fig. 45), Kittiwake (Larus argentatus and L. tridac- 

 tylus), and a few other species, which breed on the 

 coast, sometimes show themselves inland, especially 

 in stormy weather ; they then pursue field-voles, and 

 catch many injurious insects. 



